onsemi LM78L12ACZ

Overview

LM78L12ACZ from ON Semiconductor is a fixed-output, 3-terminal positive linear voltage regulator delivering 12 V ±5% at up to 100 mA, featuring thermal overload protection and short-circuit current limiting in a TO-92 package. It operates across –40°C to +125°C and maintains stable regulation with ≤250 mV line regulation (14.5–27 V input) and ≤100 mV load regulation (1–100 mA).

For engineers reviewing the LM78L12ACZ datasheet, pinout, applications, or equivalent options, this device serves as a compact, thermally protected DC power source for low-current analog circuitry, microcontroller peripherals, and sensor biasing where simplicity, reliability, and wide temperature operation are essential.

Technical Context

The LM78L12ACZ integrates a precision reference, error amplifier, series pass transistor, and protection circuitry-including thermal shutdown and foldback current limiting-within a monolithic silicon die. Its internal architecture delivers fixed 12 V output without external components beyond recommended input/output bypass capacitors (0.33 μF and 0.1 μF).

It requires a minimum input-to-output differential of 1.7 V (dropout voltage) and achieves 37–65 dB ripple rejection at 120 Hz under typical conditions. Quiescent current remains low (2.1–6.0 mA), enabling efficient operation in battery-adjacent or standby-sensitive designs.

Key Specifications

Pinout & Package

LM78L12ACZ uses the industry-standard TO-92 plastic package (3-lead, through-hole). Lead spacing and mechanical dimensions comply with JEDEC TO-243 variation AA. Thermal resistance is R_θJA = 150°C/W (still air) and R_θJC = 50°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with LM78L12ACZ, MC78L12ACP offers identical performance in the same TO-92 package with updated branding, while LM78L12ACDX provides identical regulation in a surface-mount form factor-requiring layout revision but enabling higher assembly efficiency.

Availability

LM78L12ACZ is available at Aetrix Electronics and suitable for industrial sensor interfaces, automotive body control modules, and legacy instrument cluster designs requiring stable component supply, long-lifecycle support, and consistent parametric performance across temperature extremes.

Supply support for LM78L12ACZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The LM78LXXA series was designed as a cost-effective, thermally robust family of 100 mA fixed-voltage regulators targeting legacy and new designs needing plug-and-play DC power without external feedback components.

FAQ

What is the maximum input voltage for LM78L12ACZ?

The absolute maximum input voltage for LM78L12ACZ is 35 V when operating at VO = 12 V. However, for reliable continuous operation, the recommended input range is 14.5 V to 27 V to maintain ≥1.7 V dropout margin and avoid exceeding the 0.75 W power dissipation limit under worst-case thermal conditions.

Does LM78L12ACZ require external capacitors?

Yes, LM78L12ACZ requires a 0.33 μF input capacitor (CI) placed close to the input pin to prevent oscillation, especially if the regulator is located more than ~2 inches from the main filter capacitor. A 0.1 μF output capacitor (CO) is recommended to improve transient response-even though it is not required for stability.

Can LM78L12ACZ be used in automotive under-hood applications?

Yes, LM78L12ACZ is rated for operation from –40°C to +125°C and features thermal shutdown and short-circuit protection-making it suitable for under-hood automotive applications such as body control modules and sensor signal conditioning, provided PCB copper area and airflow meet thermal resistance requirements (R_θJA = 150°C/W).

What is the dropout voltage of LM78L12ACZ?

The dropout voltage of LM78L12ACZ is 1.7 V at TJ = 25°C. This means the input voltage must remain at least 1.7 V above the nominal 12 V output (i.e., ≥13.7 V) to maintain regulation. At elevated temperatures or full load, the effective dropout may increase slightly due to internal transistor characteristics.

Is LM78L12ACZ pin-compatible with other LM78LXXA variants?

Yes, all LM78LXXA variants-including LM78L05ACZ, LM78L08ACZ, and LM78L15ACZ-share identical TO-92 pinout (Pin 1 = Output, Pin 2 = GND, Pin 3 = Input), enabling direct substitution in existing layouts when only output voltage differs. No PCB changes are needed when swapping between these variants.